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Search Results: 1 - 10 of 11785 matches for " Knock-Down Factor "
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Post-Buckling Behavior of Laminated Composite Cylindrical Shells Subjected to Axial, Bending and Torsion Loads  [PDF]
Yengula Venkata Narayana, Jagadish Babu Gunda, Ravinder Reddy Pinninti, Markandeya Ravvala
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.34019
Abstract: In present work, post-buckling behavior of imperfect (of eigen form) laminated composite cylindrical shells with different L/D and R/t ratios subjected to axial, bending and torsion loads has been investigated by using an equilibrium path approach in the finite element analysis. The Newton-Raphson approach as well as the arc-length approach is used to ensure the correctness of the equilibrium paths up to the limit point load. Post-buckling behavior of imperfect cylindrical shells with different L/D and R/t ratios of interest is obtained and the theoretical knock-down factors are reported for the considered cylindrical shells.
RNAi-mediated knocking-down ofrlpk2 gene retarded soybean leaf senescence
Xiaoping Li,Yuanyuan Ma,Pengli Li,Liwen Zhang,Yong Wang,Ren Zhang,Ningning Wang
Chinese Science Bulletin , 2005, DOI: 10.1007/BF03183696
Abstract: Leaf senescence that occurs in the last stage of leaf development is a genetically programmed process. It is very significant to elucidate the molecular mechanisms that control the initiation and progression of leaf senescence and the way the senescence signal is transduced. In a previous study on artificially induced soybean leaf senescence, we cloned a novel gene designatedrlpk2 (Genbank Accession No. AY687391) that encodes a leucine-rich repeat (LRR) receptor like protein kinase. The expression level ofrlpk2 gene was shown to be strongly up-regulated during both the natural leaf senescence process in this report and the artificially induced primary-leaf-senescence process in our previous work. The RNA interference (RNAi)-mediated knocking-down ofrlpk2 dramatically retarded both the natural and nutrient deficiency-induced leaf senescence in transgenic soybean. The transgenic leaves showed more cell-aggregated surface structure and higher content of chlorophyll.
Multiple gene knock-down by a single lentiviral vector expressing an array of short hairpin RNAs
Stove,Veronique; Smits,Kaatje; Naessens,Evelien; Plum,Jean; Verhasselt,Bruno;
Electronic Journal of Biotechnology , 2006,
Abstract: rna interference (rnai), mediated by short double-stranded rnas, is a powerful mechanism for posttranscriptional gene silencing. sustained expression of short hairpin rna (shrna) can be accomplished in mammalian cells by viral delivery systems. using lentiviral constructs, stable gene silencing is established both in dividing and non-dividing cells. targeting one single gene can lead to the development of escape mutants or may be insufficient to silence redundant pathways. therefore, simultaneous targeting of multiple genes may be necessary. we have generated a lentiviral vector-based system for expression of multiple shrnas from a single viral vector, which also encodes an egfp reporter protein. we show that knock-down of each single gene from multiple target vectors is achieved at an efficiency comparable to that obtained after transduction using single target viral vectors. in this way, we were able to knock-down several members of the human rho-family gtpases in t cells. double and triple knock-down persisted after multiple passages of the cells. the ability to inhibit two or more genes simultaneously from one single expression vector further widens the application spectrum of rnai, both in functional studies and therapeutic strategies.
Type 7 Adenylyl Cyclase is Involved in the Ethanol and CRF Sensitivity of GABAergic Synapses in Mouse Central Amygdala
Maureen T. Cruz,Michal Bajo,Marisa Roberto
Frontiers in Neuroscience , 2011, DOI: 10.3389/fnins.2010.00207
Abstract: The GABAergic system in the central amygdala (CeA) plays a major role in ethanol dependence and in the anxiogenic response to ethanol withdrawal. Previously, we found that both ethanol and corticotropin releasing factor (CRF) increase GABAergic transmission in mouse and rat CeA neurons, in part by enhancing the release of GABA via activation of presynaptic CRF1 receptors. CRF1 receptors are coupled to the enzyme adenylyl cyclase (AC), which produces the second messenger cyclic AMP. There are nine isoforms of AC, but we recently found that CRF1 receptors in the pituitary were coupled to the Type 7 AC (AC7). Therefore, using an in vitro electrophysiological approach in brain slices, here we have investigated a possible role of the AC7 signaling pathway in ethanol and CRF effects on CeA GABAergic synapses of genetically modified mice with diminished brain Adcy7 activity (HET) compared to their littermate male wild-type (WT) mice. We found no significant differences in basal membrane properties, mean baseline amplitude of evoked GABAA receptor-mediated inhibitory postsynaptic potentials (IPSPs), or paired-pulse facilitation (PPF) of GABAA-IPSPs between HET and WT mice. In CeA neurons of WT mice, ethanol superfusion significantly augmented (by 39%) GABAA-IPSPs and decreased PPF (by 25%), suggesting increased presynaptic GABA release. However, these effects were absent in HET mice. CRF superfusion also significantly augmented IPSPs (by 38%) and decreased PPF (by 23%) in WT CeA neurons, and still elicited a significant but smaller (by 13%) increase of IPSP amplitude, but no effect on PPF, in HET mice. These electrophysiological data suggest that AC7 plays an important role in ethanol and CRF modulation of presynaptic GABA release in CeA and thus may underlie ethanol-related behaviors such as anxiety and dependence.
慢病毒介导的CYP3A11基因knock-down小鼠的建立
庞浩,刘昌峨,刘勤,王露露,郭科男,王勇,魏泓
第三军医大学学报 , 2010,
Abstract: 目的构建和筛选小鼠P4503A11基因miRRNAi慢病毒载体,建立CYP3A11基因knock-down小鼠。?方法利用RaviSachidanandam’sLab的在线软件设计沉默小鼠P4503A11基因的miRNA所对应的shRNA序列,PCR扩增后克隆到PCI-GFP-MiR质粒中,其再与慢病毒载体FUW进行重组。将psPAX2和pMD2.G两个载体和FUW-GFP-MiR-shRNA重组慢病毒载体共转染293FT细胞,包装成病毒。用包装好的病毒液感染293FT细胞后,并利用GFP蛋白表达水平进行滴度测定。将上述重组慢病毒载体分别转染FVB/N小鼠肝细胞,转染48h后,检测P4503A11基因mRNA表达水平的变化。选取干扰效果最好的FUW-GFP-MiR-shRNA1重组慢病毒载体进行制备基因knock-down小鼠模型。用显微注射法将浓缩的shRNA1病毒液注射至FVB/N小鼠12细胞期胚胎透明带下。将注射后发育至22细胞期的胚胎移植至假孕受体母鼠,得F0代小鼠。在紫外光照射下利用滤光片观察GFP在小鼠活体内的表达水平。结果DNA测序结果显示3个重组慢病毒载体均与所设计的shRNA序列一致。检测的3个浓缩前慢病毒悬液的滴度均≥106TU/ml,经过高速离心对病毒进行浓缩和纯化,其滴度达到109TU/ml以上。转染FUW-GFP-MiR-shRNA1、2的2组肝细胞的P4503A11基因mRNA表达水平相对于空白对照组均显著下降(P<0.05),而转染阴性对照FUW-GFP-MiR-shRNA-NC的肝细胞P4503A11基因mRNA表达水平相对于空白对照组无明显改变。选用FUW-GFP-MiR-shRNA1慢病毒载体制备的F0代3A11基因knock-down小鼠,在紫外光照射下,阳性小鼠可见较强的荧光。结论构建并筛选出小鼠P4503A11基因有效的靶向miRRNAi慢病毒载体,并成功建立CYP3A11基因knock-down小鼠。?
Monitoring of resistance to the pyrethroid cypermethrin in Brazilian Aedes aegypti (Diptera: Culicidae) populations collected between 2001 and 2003
da-Cunha, Marcella Pereira;Lima, José Bento Pereira;Brogdon, William G;Moya, Gonzalo Efrain;Valle, Denise;
Memórias do Instituto Oswaldo Cruz , 2005, DOI: 10.1590/S0074-02762005000400017
Abstract: resistance to cypermethrin of different aedes aegypti brazilian populations, collected at two successive periods (2001 and 2002/2003), was monitored using the insecticide-coated bottles bioassay. slight modifications were included in the method to discriminate between mortality and the knock down effect. although this pyrethroid was recently started to be used in the country to control the dengue vector, a decrease in susceptibility was noted between both periods analyzed, particularly in the city of rio de janeiro. the results indicate that resistance is due at least in part to a target site alteration.
Side chain modified peptide nucleic acids (PNA) for knock-down of six3 in medaka embryos
Dorn Sebastian,Aghaallaei Narges,Jung Gerlinde,Bajoghli Baubak
BMC Biotechnology , 2012, DOI: 10.1186/1472-6750-12-50
Abstract: Background Synthetic antisense molecules have an enormous potential for therapeutic applications in humans. The major aim of such strategies is to specifically interfere with gene function, thus modulating cellular pathways according to the therapeutic demands. Among the molecules which can block mRNA function in a sequence specific manner are peptide nucleic acids (PNA). They are highly stable and efficiently and selectively interact with RNA. However, some properties of non-modified aminoethyl glycine PNAs (aegPNA) hamper their in vivo applications. Results We generated new backbone modifications of PNAs, which exhibit more hydrophilic properties. When we examined the activity and specificity of these novel phosphonic ester PNAs (pePNA) molecules in medaka (Oryzias latipes) embryos, high solubility and selective binding to mRNA was observed. In particular, mixing of the novel components with aegPNA components resulted in mixed PNAs with superior properties. Injection of mixed PNAs directed against the medaka six3 gene, which is important for eye and brain development, resulted in specific six3 phenotypes. Conclusions PNAs are well established as powerful antisense molecules. Modification of the backbone with phosphonic ester side chains further improves their properties and allows the efficient knock down of a single gene in fish embryos.
Resistencia a deltametrina de cepas de Blattella germanica (Dictyoptera: Blattellidae) en la ciudad de Cali, Colombia
Piazuelo Ramírez,María Mercedes; Jaramillo Ramírez,Gloria Isabel; González Obando,Ranulfo;
Revista Cubana de Medicina Tropical , 2009,
Abstract: introduction: blattella germanica is one of the most important pests worldwide. the pest status is due to their great infestation capacity and ability to develop relative short-term insecticide resistance. since local studies about resistance on b. germanica to any insecticide have not been made, it is necessary to find out the state of resistance of this species to insecticides. the collected data will allow establishing an effective monitoring system that will improve some control measures already in place. objective: to ascertain the level of resistance to deltamethrin in some populations of b. germanica from cali (colombia). methods: five different strains of b. germanica were collected in cali (colombia), in areas with high levels of infestation. adult males and females were exposed and tested to deltamethrin using bottled bioassays. results: kc50 to pyrethroid deltametrhin was determined in adult males and females of b. germanica from cali city. males were more susceptible than females. two evaluated strains showed a high resistance factor (sports club: rt=22 for females and 13 for males; market 2: rt=14.33 for females and 13.50 for males) representing areas with history of highly frequent insecticide application. the most susceptible strain (hospital: kc50=0.03 mg/ml and 0.02 mg/ml for females and males respectively) has not been submitted to constant selection pressure with insecticides because of the likely risks of this type of application for human health in places where critically-ill patients are treated.. conclusions: this study contributed the first evidence of deltamethrin resistance in populations of b. germanica from cali (colombia). it is possible to carry on using deltamethrin in susceptible populations within an ongoing monitoring and control program.
Simulation and Characteristics Improvement of Quantum Dot Slow Light Devices by Geometrical Dimension Alteration  [PDF]
Bahram Choupanzadeh, Hassan Kaatuzian, Reza Kohandani, Saeed Abdolhosseini
Optics and Photonics Journal (OPJ) , 2016, DOI: 10.4236/opj.2016.68B019
Abstract:
In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters of slow light device and a method is presented for setting the output specifications of this kind of devices. In this paper, we deal with changing the size of quantum dot to find the ideal size. The simulation results indicate that as the size of quantum dot changes properly (with reducing more than 50 percent of quantum dots both radius and height), then the slope of diagram of the real part of refractive index increases significantly so that the Slow Down Factor (SDF) predicted to be18 times greater. Analysis and simulations based on cylinderical quantum dots structure slow light devices based on exitonic cpo.
Resistencia a deltametrina de cepas de Blattella germanica (Dictyoptera: Blattellidae) en la ciudad de Cali, Colombia Deltamethrin resistance in Blattella germanica (Dyctioptera: Blattellidae) strains from Cali city, Colombia
María Mercedes Piazuelo Ramírez,Gloria Isabel Jaramillo Ramírez,Ranulfo González Obando
Revista Cubana de Medicina Tropical , 2009,
Abstract: estatus de plaga se debe a su gran capacidad de infestación y al desarrollo de resistencia a insecticidas en corto plazo. Como no se han realizado estudios locales previos es necesario determinar el estado de la resistencia a diferentes insecticidas, datos que servirán de referencia para establecer un sistema de vigilancia que mejorará las medidas de control. OBJETIVO: establecer el estado de la resistencia al piretroide deltametrina en poblaciones de B. germanica de la ciudad de Cali (Colombia). MéTODOS: se colectaron 5 cepas de B. germanica en la ciudad de Cali, en lugares con altos niveles de infestación. Se evaluaron adultos machos y hembras de esta especie expuestos al piretroide deltametrina mediante bioensayos con botellas. RESULTADOS: en machos y hembras de B. germanica de la ciudad de Cali, se determinó la CK50 a deltametrina. Los machos fueron más susceptibles que las hembras. Dos de las cepas evaluadas presentaron un elevado factor de resistencia (Club deportivo: FR= 22 para hembras y 13 para machos; Plaza de mercado 2: FR= 14,33 para hembras y 13,5 para machos) y corresponden a áreas con una historia de mayor frecuencia de aplicación de insecticidas. La cepa más susceptible (Hospital: CK50= 0,03 mg/mL y 0,02 mg/mL para hembras y machos, respectivamente) no ha estado sometida a una presión de selección constante con insecticidas, debido a los riesgos que implican estas aplicaciones en lugares donde se encuentran pacientes con tratamientos médicos delicados. CONCLUSIONES: estos resultados constituyen el primer registro de resistencia a deltametrina en poblaciones de B. germanica en Cali (Colombia). En las poblaciones susceptibles se puede continuar la aplicación de deltametrina dentro de un programa de vigilancia y control permanente. INTRODUCTION: Blattella germanica is one of the most important pests worldwide. The pest status is due to their great infestation capacity and ability to develop relative short-term insecticide resistance. Since local studies about resistance on B. germanica to any insecticide have not been made, it is necessary to find out the state of resistance of this species to insecticides. The collected data will allow establishing an effective monitoring system that will improve some control measures already in place. OBJECTIVE: to ascertain the level of resistance to deltamethrin in some populations of B. germanica from Cali (Colombia). METHODS: five different strains of B. germanica were collected in Cali (Colombia), in areas with high levels of infestation. Adult males and females were exposed and tested to deltamethrin
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